Shaft seals are relatively new devices within the past 40 or 50 years, and in the early days lubrication was mostly in the form of splash lubrication with the oil dripping off of the parts into a sump. In automotive usages, in such early days, a felt ring was placed into a housing groove to keep the crank case oil from draining into the transmission.
As engines and other devices developed higher speeds, the problem of containing the oil became increasingly difficult. Some of the early shaft seals were made of leather wherein the manufacturer would cut a leather washer and clamp the outer diameter thereof in a metal casing. The inner diameter of the washer was cut to a diameter somewhat smaller than that of the shaft projecting through it. When the seal was installed, the metal casing was so dimensioned as to provide an interference fit in the bore of the housing, and the leather washer was so dimensioned as to provide an interference fit with the rotating shaft.
On occasion, such leather washer was sometimes supported by finger springs to give added sealing ability. The leather washer was eventually replaced by synthetic washers, from a cost view point. Later, the knife edge type of configuration for the sealing surface was developed as shown in many of the prior art patents of which I am aware such as, for example, Woodling U.S. Pat. No. 3,489,420 and Procter U.S. Pat. No. 2,316,713.
With the advent of the molded lip, a garter spring was installed to increase the sealng ability of this type of seal. In each and every case, however, of which I am aware the seal is press fitted into the bore of the housing sometimes with a metal shell with or without a rubber covering, but in all cases the rubber was bonded in some manner to the metal and this is a difficult and expensive process.
The expense involved in preparation of the metal shell and the processing and handling during the molding process is quite high. The metal must be inserted into a mold one at a time, which in itself is time consuming. The rubber compound must then be inserted into the mold, and the entire assembly molded under heat and pressure for a considerably time period. Removing the parts is difficult because the metal shells expand, due to heat. The tolerances on the shells must be held very close in order that they be able to fit metal bores without leakage while being used. The seal of the present invention is less costly because no metal insert is being handled during the molding process.
The present invention is designed to overcome the problems attendant with those seals wherein rubber is bonded to metal, both from the standpoint of expense and ease of assembling in the bore of the housing and around the shaft.